Nickel plating



Unite NICKEL PLATING Arthur H. Du Rose, Euclid, and John D. Little, Bay

Village, Ohio, assignors to The Harshaw Chemical Company, Cleveland, Ohio, a corporation of @hio No Drawing. Application February 16, 1954, Serial No. 410,714

7 Claims. (Cl. 204-49) States PatcntaO although electrodeposits taken from acid nickel plating solutions containing coumarin exhibit extraordinary smoothness they are only semi-bright, and attempts to increase their brightness by the use of addition agents of the type of saccharin or naphthalene sulfonic acids result in improved brightness with loss of smoothness when the surface being coated is quite smooth, and can result in decrease in both smoothness and brightness when the surface of be coated is quite rough. It was found, for example, that when an aqueous, acid solution containing 240 grams per liter of nickel sulfate hcptahydrate, 40

grams per liter of nickel chloride hexahydrate and 40 grams per liter of boric acid was utilized and coumarin was used in concentration of 0.25 gram per liter as the sole addition agent, a semi-bright deposit was obtained having a smoothness increase over the base metal of approximately 4 microinches where the base metal had a smoothness in the order of 6 to 10 microinches, measurements having been made with the Brush surface analyzer.

a commercial semi-bright solution now being widely used. When the attempt was made to increase the brightness by the addition of agents such as saccharin or naphthalene sulfonic acids, it was found that increased bright- I ness was secured, but at the cost of a part of the smooth- 2,782,154 Patented eh. 19,}957

2 added, in addition tothe coumarin, not only an aromatic sulfonamide, but also one or more of certain organic, leveling addition agents of the following class:

Alkylene amines and alkylene polyamines, compounds of the form NH2[(CHz)zNH]n(CHz)zNHz, where n is an integer greater than 2, preferably 12 to 40. Not only 5 unsubstituted alkylene amines but also alkylene amines raving substituents on the nitrogen may be utilized.- These compounds may be condensed with compounds such as epichlorhydrin, acrylonitrile, etc.

As examples may be mentioned,

(a) Tetraethylene pentamine (monomer) Y (b) Polymerized tetraethylene pentamine (molecular wt. 1200 f (c) Polymerized tetraethylene pentamine (molecular wt. 1800) (d) Tetraethylene pentamine condensed with acrylonitrile in molecular ratio of 1:7.

While these leveling agents do not completely restore the full smoothing action of coumarin, they do, in some in.- stances, approach that result, and in other instances restore a large portion of it. I

The preferred acid nickel solution in connection with which the invention may be realized is an aqueous solution containing nickel sulfate equivalent to'from 100 to 400 grams per liter of nickel sulfate heptahydrate, nickel chloride equivalent to from 10 to 75 grams per liter of nickel chloride hexahydrate, and from 10 to 50 grams per liter, preferably 15 to 40 grams per liter, of boric acid or other buffer such as formic acid or citric acid.- To this fundamental solution there may be added in accordance with the present invention one or'more aromatic sulfonamides to a concentration firom /2 gram per liter to saturation, one or more coumarin compounds to a concentration from 0.01 to 0.5 gram per liter, and one or more leveling agentsof the above indicated class in concentrations less than half a gram per liter, for example, from 0.0001 to 0.3 gram per liter. The concentrations of these compounds required for best results will be within the ranges indicated in the respective tables opposite each of said compounds, and very desirably will Such an increase in smoothness is remarkable, and this property of coumarin has formed the basis of an increase in brightness was secured, but the gain in smoothness over the base metal was only about 2.2 microinches, the same type of base metal being used. If, in stead of using naphthalene sulfonic acids, saccharin was used to improve the brightness, improved brightness was obtained and the gain in smoothness was about the same. Many other sulfonic acids and sulfonamides show similat' --results. When the surface to be coated is not-so smooth, e. g. 20 to 29 R. M. S. as shown by the Brush surface analyzer, the loss of the smoothing action may be so great as to overshadow the tendency toward increased brightness and actually appear to decrease the luster of the deposit.

In accordance with the present invention it has now been discovered that a large portion of the lost smoothing action just described can be restored if there is be approximately the specific concentration set forth op-' posite each compound in the tables.

The compounds listed in Table I are examples of sulfor compounds which when used in connection with coumarin and certain coumarin derivatives produce an increase in brightness with some loss in smoothness; Numerous other similar compounds produce the same efiect in varying degree. They are aromatic sulfonamides and sulfimides. The compounds of Table II are examples of coumarin compounds which'can be used. Alkyl and acyl derivatives of coumarin having 1 to 4 carbon atoms, and the chlorine and carboxy derivatives thereof are suitable. The compounds listed in Table III are examples of organic compounds effective to increase smoothing power (and brightness) of coumarin type smoothing agents lost by the addition of sulfur compounds of the type of those listed in Table I. Coumarin sulfonic acids are not equivalent to the above indicated coumarin compounds.

Preferably, the solutions are operated in pH range. from 2.5 to 4.5, the temperature is maintained within the ran ge from F. to F., and the cathode current density is maintained within the range from 5 to 100 a. s. f.

Formaldehyde may be used in the above described solutions at a concentration of from 0.05 to 0.5 gram per liter for the purpose of retarding or minimizing the effect of breakdown products of coumarin or derivative such as listed in Table II.

Specific examples which have yielded excellent results are indicated in Table IV.

Other basic solutions capable of yielding nickel ions for electrodeposition may be employed. Preferably there should be present in the solution at least one nickel salt of the class consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate. The nickel ion concentration should .in any case be within the range which would result from the presence of from 100 to 400 grams per liter .of NiSO4.7H2O.

Table 1 Optimum Preferred Range, Concentrag./1. tion, g./l.

(1) Benzene sulfonamide (PhSO1NH=) 0. 5 to 3.0 1.0 (2) p-Toluenesulfonamide (013301114502 z)- 0. 5 to 3. l. 0 (3) Snecharln (o-benzosulflmld) 0.5 to 3.0 1. 0 (4) Dibeuzene sulfonamide (PIISOZNHSOgPh) and its monoand-diehloro derivatives 0 5 to 3. 0 1. 0 (5) p-Benzene-bie (N-sulphonylbcnzenosiilfonamtde (PhsOzNHSOgOeHtSOzNHSOgPi!) 0. 5 to 0. 0 .0 (6) N-ethune sulfonyl benzene sultonamide. 0.5 to 0 1. 0 (7) Monoand dt-ehlorohenzene sltlfonamides. 0. 01.0 5. 0 0 (8) Monoand di-chloro derivatives of (2) and (5) above e- 0. 5 to 5. 0 1.0 (0) Bl-dibenzenesulfonamide (PllSOzNHSOr CQHQCEHSOINHSOQPTI) U. 5 0O "7. 0 l (l (10) Monoand di'chloro derivatives of (9) above 0 5 to 5.0 1.0 (11) Dibenzono sulionamide other 3' NHSOQC H4OC H;SO;NHSO P11) 0. 5 to .0 1. 0

Table II Preferred Range, gJl. Concentration, g./l.

Coumarin 0.05 to 0.25 0. i 3-Chlorocoumerm" 0.05 to 0.25 0. 1 B-Chioro coumarm" 0.05 to 0. 25 0.1 s-metbyl coumarim- 0.05 to 0.25 0. 1 fi-carboxy coumarin 0.05 to 0. 25 0. 1

Table III Preferred Range, g./l. Concentrntion, g./l.

(I) Tetraethylene pentamine(mono1ner) .0001 to .1 .02 (2) Polymcrized tetrnethylene pentamine (M. W. 1, p0) .0001 to .1 .005 (3) Polymerized tetraethylene pentainine (M. \V. 1,800) .0001 to l .000 (4) Tetraethylene pentarnine condensed with acrylonitrile in molecular ratio 0t1:7 .0001 to 1 .00075 (5) 'Ietraethylene pentamino condensed with epichlorhydrin in molecular ratio of1:2 .0001 10.1 .01

Table IV Grams per Liter NiSO4.THzO 300 300 300 NiClz.0HaO.. 45 45 45 H1130: =10 40 40 Sodium lauryl sulfate Coumarin l Saccharin Toluene sulionamidc. Dibenzene sulionamide. Tetraethylene pentam ne (In *r) Tetrnethylene pentamine (M. W.

Having thus described the invention, what is claimed is:

1. A solution for electrodeposition of nickel in the form of bright and smooth deposits, said solution containing a nickel ion yielding compound of the class consisting of nickel sulfate, nickel chloride, nickel sulfamate and nickel fluoborate together with cooperating addition agents, one of said addition agents being an organic sulfur compound containing the group one thereof being selected from the class consisting of couma-rin and its alkyl, acyl, chlorine and carboxy derivatives and a third thereof being an alkylene amine of the form NH2[(CH2)2NH]11.(CH2)2NH2, Where n is an integer from 2 to 40, said first mentioned addition agent being present in concentration from one-half gram per liter to saturation, said second mentioned addition agent being present in concentration from 0.01 to 0.5 gram per liter and said third mentioned addition agent being present in concentration from 0.0001 to 0.3 gram per liter.

2. A process for producing bright, smooth electrodeposits of nickel comprising electrolyzing between an anode and a cathode a solution containing nickel sulfate equivalent to from 100 to 400 grams per liter of nickel sulfate heptahydrate, nickel chloride equivalent to from 10 to grams per liter of nickel chloride hexahydrate and a group of three cooperating addition agents, one of said addition agents being an organic sulfur compound containing the group 1 I one thereof being selected from the class consisting of cournarin and its alkyl, acyl, chlorine and carboxy derivatives and a third thereof being an alkylene amine of the form NH2[(CH2)2NH]n(CH2)zNHz, where n is an integer from 2 to 40, said first mentioned addition agent being present in concentration from one-half gram per liter to saturation, said second mentioned addition agent being present in concentration from 0.01 to 0.5 gram per liter and said third mentioned addition agent being present in concentration from 0.0001 to 0.3 gram per liter.

3. A process according to claim 2 wherein said solution contains from 10 to 50 grams per liter of boric acid.

4. The invention as defined in claimed 2 wherein n is an integer from 12 to 40.

5. The invention defined in claim 2 wherein said organic sulfur compound is dibenzene sulfonamide.

6. The invention defined in claim 2 wherein said organic sulfur compound is bidibenzene sulfonamide.

7. The invention as defined in claim 2 wherein the third mentioned addition agent is present in concentration from 0.0001 to 0.1 gram per liter.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SOLUTION FOR ELECTRODEPOSITION OF NICKEL IN THE FORM OF BRIGHT AND SMOOTH DEPOSITS, SAID SOLUTION CONTAINING A NICKEL ION YIELDING COMPOUND OF THE CLASS CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, NICKEL SULFAMATE AND NICKEL FLUOBORATE TOGETHER WITH COOPERATING ADDITION AGENTS, ONE OF SAID ADDITION AGENTS BEING AN ORGANIC SULFUR COMPOUND CONTAINING THE GROUP 